Continuous polymerizing apparatus



Oct. 21, 1952 l, ALLEN, JR, Erm. 2,514,910

CONTINUOUS POLYMERIZING APPARATUS Filed June 14, 1949 |NVENTOR5 n/EY ALLEN, JRA WALTER RMARSHALL GOD WICHTMAN ATTOR 'l Patented Oct. 21, 1952 UNITED STATES PATENT "oFF1ca-*-f Ivey Allen, Jr., andl Walter:RrMarshalL` Bloom- 1,

. ield,lN. J., and Gordon E. WightmamNewburgh, N. Y., assignors, by mesne assignments, to Union Carbide and Carbon Corporation, a

corporation of evv'York Amiiicatiqn` June i4, 1949,` serial ive. 98,959

Ihisinvention` relates to apparatussuitable `for continuous polymerization of` unsaturated` organic `compounds to solid resinous polymers. In general` the unsaturated compounds are vinyl monomers, such as vinyl acetate, vinyl butyrate. styrene, chloro-styrenes, methyl, ethyl andpropyl styrenea,vinylnaphthalene, etc. ,n

More` particularly.V the invention comprises an apparatus assembly for accomplishing in a continuous manner the progressivesteps of (a)` initially polymerizing a monomer at'atemperature yielding polymers of desired averagemolecular weight while subjecting` the,` monomer and polymers formed to eiective agitation, (b) completing` the polymerization by heating amoving stream of partiallylpolymerized material to rela.- tively high temperatures, and (-c) mechanically milling the polymerized material to remove volatiles and low `molecular weight `polymers therefrom.

l An apparatus for the continuous polymerization of a polymerizable-monomer and `embodying structure for accomplishing the aforementioned improvements is illustrated in `the accompanying drawing in which Fig. 1 is an elevationlargely in cross-section of an assembly;v I

Fig. 2 is a cross-sectiononthe line 2--2 of Fig. l; and

Fig.` 3 isa cross-sectionon the line` 3-3 Fig; 1. I l n The assembled apparatus is comprised of Vthree primary'parts: 1 3 l I A.. An autoclavewith` associated elements for partial polymerization; ,I

lB. `A polymerizing,r tube `for continuing polymerization; and` C. A` milling structure for mechanically worling thepolymerized polymer and releasing vola-` tilematter therefrom.

Part I A The autoclave part consists ofa closed still body or reaction vessel II'I having about `its-lower portion a jacketi I for heating or cooling fluid to regulate the temperature; the still has a capacity of about 800 pounds. Passing through abushing I2 at the top of the VVstillis a vertical agitator shaft` I3Which carries fa series of agitator blades I4; I5 and I6A of which` the upper and` lower blades I4 and I6 are fastened to the shaft I3, to be rotated thereby. The middleset of blades` I5 are stationary being rigidly secured to `theinterior walls ofthe autoclave. Thefhub to-which the blades I5 are attached, `serves as a bearing for the agitator shaft 1a which ends in a conthe veyor screw Ilfextending into the outletfIB" `of the still and into ajacketed coupling |95' ,"Because ofthe high viscosity of the' polymer formedthe agitator structure is rugged and heavy. l

The upper` rotating blades I4 are inclined baclmvardly` with` respect to the direction pieroL tationv to force partially polymerized monomer outwardly; theblades Ill are also inclined downwardly in the direction or rotation to force the outwardly directed material concurrently j in a downward" direction along e the autoclave walls. The stationary blades I5 have. a twisted shape whereby the outer end of each blade `is inclined downwardly land forwardly with' `respect tothe directi'oirof rotation of the upper rotating blades I4 `and thedownwardmovement of material along the autoclave walls. The inner end ofeach staL tionaryblade I5 is inclined upwardlyand #forfwar'dly. l Q-f the' series of agitator bladeatheitop,blades` I4` vserve to force the mass in movements outward ly tand downwardly along the, autoclave's walls", the intermediate iixed blades I5` accentuate this action at their outer ends while causinganup ward flow near the'shaft, and the bottom lblades IB (shown in Fig. 2) scrapeythe mass. from the sides` and force` it inwardlyjtoward' the"`sha'ft Where part of the mass is directed upwardly along the shaft and the balance downwardly'out ofthe outlet I8..` Additional intermediate rotatingfand stationary blade agitatorscan be in; cluded.` The upper end of thershaft is connected by"a gear reducer 20 to armotor onotherdriv ingmeehanism notl shown; jffl `.fitltheupper end of the still is an outletv `pipe Ziffer distillate controlled by a valve' 22"i`and leading to a condenser 23. The condenser has a vapor-discharge line 24 with control 'va1ve25 leading to a vacuum pumpl (not'showni anda condensate-discharge line 26` having thereinja sight glass 21 for observation.` Two branches 28. 29` with valves 30, `3l connect tothe line 26; and one branch 29, providedfwith a trap. 32 and discharge valve 33, leads back to the sti11.`

Liquid monomer is drawn intothe'still thro-ugh afeed line` 34 controlled by a valve 35eV from a feed drum 3E.` In the line is a rotameter'lfto indicatethe rate at which the monomer `iiovws into the still. y In thesideof the still IU is a tube 38' for" receiving a thermometer. The still also has` a` sight glass 39 for watching the operation.

PartV B R first section is a tubular preheater 40 with a heating jacket 4l and carrying an axially-disposed mandrel 42 by means of fins 43 to form an annular passage through which the plastic flows. The second section is a first reaction tube 44 with a heating jacket 45. The third section is a coupling 46' supporting a spindle shaped hollow heating element 41 by fins 48 to leave an annular passage; an inlet pipe 49 and an outlet pipe 55 to the heating element 41 provide for a heating iiuid into and out of the interior thereof. The

fourth section is a second reaction tube l with Part C Attached to the funnel 53 forming the outlet' of the polymerizer B is an enclosed continuous vacuum roll-mill for mechanically working the polymerized product. It consists of three sections; a hopper 6|, a housing 62 and a closure casting' 63. The hopper has a slide gate G4 Afor controlling the feed of polymerized 'plastic'.V A pair of intermeshing h'elically-threaded rolls 55, 56 "(Fig. 2) extend from the hopper f5| and through an opening 6l into the housing 62; these rolls lie in the saddle-shaped bore E58 and have a close vclearance with the sides of the bore which extend within a part of the housing over'at least 'one-'half the circumference of the rolls; the rolls yare completely encircled at the entrance to and theexit from the housing. The rolls are supported' at thefreceiving end by stub shafts journaled in bearings in the wall 69 of the hopper. and at the other end by shaftextensions 'l0 passing'v through bearings in the casting 63. The Ascrews for their major length have V or' other suitable form of milling threads; but at the discharge end they are given square threads `and completely enclosed toprovide a Apositive pumping action. Above the V thread portions there is chamber 'H with an outlet 'l2 for connection toa condenser, vacuum pump and receiver; and 4a tube 13 opens into the chamber for feeding inert gas. The chamber has a surroundingheat'- ing jacket 14. tThere is; an outlet port through .the casting 63;",and sight glasses 15 are provided inthe housing 62. i j I VInjoperati'ng the assembled apparatus, liquid monomer is continuouslyfed into the still from the drum 36 through 'the pipe 34. vIn its progress through the still it becomes polymerized bythe heat of polymerization which is more than enough to continue the action; the excess heatl is removed and the desired' temperature maintained by the degree of vacuum (1S-22 inches'mercury), applied which regulates the'boiling point of the monomer. The agitator blades direct and redistribute the mass; and as the'l product is withdrawn through the outlet I8, there is a gradual oonstant overall movement downwardlythrough the still. along with a continuous recycling acf` tion Within the mass.

The bottom agitator blades I6 and the screw conveyor Il regulate the discharge fromithe still and force it into the preheater of the polymerizing tube B'.v Here it is quickly raised in temperature to progress through the first reaction sec-V tion 44. Further` heating by the heating vele# mentttl increases its mobility for further r'low through the second reaction tube 5I and final discharge through the funnel 53 and gate S4 into the `milling machine. The operation of the threaded rolls combines ,the functions ofv milling and..conveying...The

' milled polymer through the port '15. eration both the entrance and exit openings are 4 threads become coated with polymer and continually expose fresh polymer surfaces collected from the small pools of churning excess material carried in the thread grooves Within the bore through the opening 6l. vThe rolls are preferably rotated in counter directions to drawsome of the polymer material'preferablyupvvard through the clearance between the intermeshing threads while the remainder is conveyed toward the discharge end., The square threads at the discharge end act as a positive pump to eject the In the opsealed by the polymer material, so that a high Vvacuum V(29'-29.9 inches of mercury) can be maintained in the housing. While the milling actionis going on, the interior is swept by aV stream of nitrogen to carry off released volatiles to the receiver, and the .removal of volatiles can be accentuated by the vacuum application.

The hot polymer is discharged'through orifices in a plate at the exit end of the -roll-millhousing and picked up on a series of pulleysoperated at such a speed as to reduce the cross-section area and give the material a stretch in excess of fifty per cent and usually of about 300 percent during cooling. '-The cooled rodthen passes to a cutter where it is' 'cut continuously into'segments of the length desired for commercial molding and extrusion operations. This application is a continuation-in-part of our (so-pending application Serial No. 505,908 filed OctoberlZ, 1943, 4nov/Patent No. 2,496,653.

Whatis claimedv is: w Y l. Polyme'rizing apparatus comprising incombination, an autoclave shell having a surface of revolution provided with an inlet and an outlet, an agitator shaft journaled-in said shell coaxial with said surface of revolution, agitator blades mounted on said shaft to rotate therewith inside said shell, an elongated jacketed tubular extension of smaller diameter thansaid shell andvse cured theretoiny position surrounding said outlet and extendingtherefrom a greater length than said shell, and an enclosed-kneading device com-J v prising alcasing securedto vthe discharge endof said jacketed tubular extension land having Ta rotating kneading element journaled in said casing.

2. Polymerizin'g apparatus comprising in combination,an autoclave shell having a surface of revolutions, an agitator shaft journaled in said shell coaxial with said surface of revolution, agi`v tator blades mounted on-said Ashaft to rotate therewith inside said shell, anelongated jacketed' tubular extension of smaller diameter than said shell secured to the bottom thereof coaxial-With said vshaftand surrounding the discharge outlet of said shell, the lower end "of said shafte'xtending down into said tubularextens'ion, a screw conveyor on said shaft extension inside said jacketed tubular extension, and an enclosed kneadingdevice comprising a casing secured to the discharge end of said jacketed tubular ex` tension and having a rotating kneading element journaled therein. l

3. Polymerizing apparatus comprising in com# bination, an; autoclave lshell having a surface of revolution provided with'an inlet and an outlet, an agitator shaft journaled in said shell coaxial with said surface of revolution, agitator blades mounted onsaid shaft to rotate-therewith inside said` shell, an elongated jacketed tubular exten` sion of smaller diameter than said shell and s'ecured lthereto in position surrounding said outlet,

a member mounted inside said tubular extension by fins to form an annular passage, and an ericlosed kneading device comprising a casing secured to the discharge end of said jacketed tubular extension and having a rotating kneading element journaled therein.

4. Polymerizing apparatus comprising in combination, an autoclave shell having a surface 0f revolution provided with an inlet and an outlet, an agitator shaft journaled in said shell coaxial with said surface of revolution, rotating agitator blades mounted on said shaft inside said shell and inclined backwardly and downwardly with respect to the direction of rotation and cooperating with fixed stationary blades secured to the inner wall of said shell, an elongated jacketed tubular extension of smaller diameter than said shell and secured thereto in position surrounding said outlet, and an enclosed kneading device comprising a casing secured to the discharge end of said jacketed tubular extension and having a rotating kneading element journaled in said casing. y

5. Polymerizing apparatus comprising in combination, an autoclave shell having a surface of revolution provided with an inlet and an outlet, an agitator shaft journaled in said shell coaxial with said surface of revolution, rotary agitator blades on said shaft inside said shell cooperating with fixed stationary blades inclined downwardly and forwardly with respect to the direction of rotation and secured to the inner wall of said shell, an elongated jacketed tubular extension of smaller diameter than said shell and secured thereto in position surrounding said outlet, and an enclosed kneading device comprising a casing secured to the discharge end of said jacketed tubular extension and having a rotating kneading element journaled in said casing.

6. Polymerizing apparatus comprising in combinaton, an autoclave shell having a surface of revolution provided with an inlet and an outlet, an agitator shaft journaled in said shell coaxial with said surface of revolution, rotating agitator blades on said shaft inside said shell cooperating 6 with fixed stationary blades secured to the inner wall of said shell, a lower set of said rotating blades conforming to the shape of the bottom of the shell and concave in the direction of rotation, an elongated jacketed tubular extension of smaller diameter than said shell and secured thereto in position surrounding said outlet, and an enclosed kneading device comprising a casing secured to the discharge end of said jacketed tubular extension and having a rotating kneading element journaled in said casing.

'7. Polymerizing apparatus comprising in combination, an autoclave shell having a surface of revolution provided with an inlet and an outlet, an agitator shaft journaled in said shell coaxial with said surface of revolution, agitator blades mounted on said shaft to rotate therewith inside said shell, an elongated jacketed tubular extension of smaller diameter than said shell and secured thereto in position surrounding said outlet, an enclosed kneading device comprising a casing secured to the discharge end of said jacketed tubular extension and having a rotating kneading element journaled in said casing and a tube connected to said casing for removing volatile material from polymers discharged from said jacketed tubular extension.

IVEY ALLEN, JR. WALTER R. MARSHALL. GORDON E. WIGHTMAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,450,326 Maitland Apr. 3, 1923 1,598,185 Willard Aug. 31, 1926 1,818,372 Battilani Aug. 11, 1931 2,273,822 Allen Feb. 24, 1942 2,340,834 Hanson Feb. l, 1944 2,435,228 Mann Feb. 3, 1948 2,496,653 Allen et al. Feb. 7, 1950 

1. POLYMERIZING APPARATUS COMPRISING IN COMBINATION, AN AUTOCLAVE SHELL HAVING A SURFACE OF REVOLUTION PROVIDE WITH AN INLET AND AN OUTLET, AN AGITATOR SHAFT JOURNALED IN SAID SHELL COAXIAL WITH SAID SURFACE OF REVOLUTION, AGITATOR BLADES MOUNTED ON SAID SHAFT TO ROTATE THEREWITH INSIDE SAID SHELL, AN ELONGATED JACKED TUBULAR EXTENSION OF SMALLER DIAMETER THAN SAID SHELL AN SECURED THERETO IN POSITION SURROUNDING SAID OUTLET AND EXTENDING THEREFROM A GREATER LENGTH THAN SAID SHELL, AND AN ENCLOSED KNEADING DEVICE COMPRISING A CASING SECURED TO THE DISCHARGE END OF SAID JACKETED TUBULAR EXTENSION AND HAVING A ROTATING KNEADING ELEMENT JOURNALED IN SAID CASING. 